This invention relates generally to fire extinguishing compositions, particularly those which may be used in handheld, portable fire extinguishers, and to methods of extinguishing fires.
Fire extinguishing compositions are well known. These compositions are applied to a fire to extinguish the fire to various degrees of effectiveness depending upon the particular composition used. Gaseous fire extinguishing compositions are also well known. There exists, for example, a fire extinguishing composition comprising bromochlorodifluoromethane as the extinguishing agent (or extinguishant) and nitrogen gas as the expelling agent (or expellant). The use of such a composition also requires the presence of a pressure gauge on the fire extinguisher to detect leaks of the nitrogen gas or bromochlorodifluoromethane into the atmosphere. The leakage problem is particularly acute with nitrogen gas because of the relatively small size and weight of this molecule as compared to bromochlorodifluoromethane.
The use of a pressure gauge on a portable, hand-held fire extinguisher which is designed primarily for household use is particularly undesirable not only because of the added expense involved in supplying each fire extinguisher with a pressure gauge, but also because of the practical difficulty involved in attaching a pressure gauge and still having a portable, hand-held, inexpensive, yet effective, fire extinguisher for home use.
The use of bromotrifluoromethane as a fire extinguishant is also well known. This compound is relatively much more expensive than bromochlorodifluoromethane. For that reason alone, the use of bromotrifluoromethane in a fire extinguishing composition is not preferred. The use of combinations of bromotrifluoromethane and bromochlorodifluoromethane as fire suppressants has been reported. Breen, David E. "Combinations of Halons 1301 and 1211 as Fire Suppressants" in Factory Mutual Research Technical Report, May, 1975.
The use of bromotrifluoromethane and bromochlorodifluoromethane as an extinguishing composition in a relatively small fire extinguisher was described by Kung in U.S. Pat. No. 4,226,728.
The use of non-fluorocarbon propellants, e.g. propane, or inert gas additives, e.g. carbon dioxide or nitrogen, as propellants for effective dispensing is well known. Propellants are used especially at very low temperatures, for example, -40.degree. F.
The search has continued for a portable, hand-held, inexpensive fire extinguisher which contains a composition which will effectively be dispensed at a wide range of temperatures to extinguish fires but which does not require the use of a pressure gauge to determine gas leaks or propellants for effective dispensing. This invention was made as a result of that search.